The nineteenth and twentieth centuries have seen human population grow exponentially. With this growth have come demands for food, shelter and resources. As these needs are met, fragile ecosystems worldwide can suffer. Natural habitats are shrinking, and some scientists say that 25% of all plant and animal species will become extinct in just fifty years. This program looks at the methods and research of scientists who are studying the biodiversity of our planet. Understanding Biodiversity is the first step in learning how we can preserve earth's intricate web of life while meeting human needs.